The balancing of vehicle wheels or other rotating parts is at the present time effected with the aid of machines comprising a shaft intended to support the wheel and driven rotationally, being mounted in two bearings spaced apart and each provided with a force sensor. A device enables the rotation of the shaft to be monitored continuously, while a computer receiving information from this device and also the signals coming from the sensors determines the correction masses to be attached to the wheel on the basis of a relationship dependent on the diameter of the wheel, its speed of rotation, as well as on the sensitivity of the sensors, the distance between bearings, the distance between the first bearing and the nearer side of the wheel rim, and the width of the wheel.
The operator must therefore measure the diameter of the wheel, the width of the rim, and the distance between the first bearing and the rim by means of potentiometers, keyboards, or any other appropriate device, thereby entailing a risk of mismeasurement and the inputting of incorrect data into the computer.
It should in addition be observed that the speed of rotation, the sensitivity of the sensors, and the distance between bearings are considered as constants for a determined machine. However, the speed of rotation varies as a function of the mains voltage and frequency, while the sensitivity of the sensors may vary with the weather or temperature, so that additional inaccuracy occurs in the measurement.